Using airsonic (Linux) to serve music to ultrasonic (android) via sniproxy (to make my ip6 web servers available over ipv4) I finally have music streaming from my home media collection to my 4g phone. And the UI is not awful either

Writeup to follow

self reply

To add to that software shopping list: beets https://beets.readthedocs.io/ . Airsonic likes to present the music according to directory structure instead of using the metadata (id3 tags etc), so I have used beet import to spruce up the tags using musicbrainz and to reorganise it all into a music/artist/album name/songname.flac structure. Greatly improved, and found a bunch of music I didn't know I had

restic kicked off about 70% of the way through, this is going to be the biggest backup job I've run for a little while :-/